How will new aircraft with composite materials withstand a crash?

Discussion in 'General Discussion | Travel' started by milchap, Jul 7, 2013.  |  Print Topic

  1. milchap
    Original Member

    milchap Gold Member

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    After the initial shock of Asiana 214, I could not help but ponder the question will new aircraft with composite materials withstand the forces experienced in SFO?

    My question is not to debate the safety of the 787 but to open a discussion on how composite materials will react to such an impact.
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  2. MX

    MX Gold Member

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    If you're pondering strictly the mechanical characteristics of the materials, there's actually a lot of comparative field data most of which came from outside of aviation. After the California airspace industry went bust, innovation in the aircraft materials development was stifled for decades. Many of the carbon-epoxy composite experts went on to work in other areas, most notably bicycle frame building. Now the best bike frames come in carbon composites, aluminum, and titanium. In the last 30 years, the bike building industry accumulated lots of stress and failure data in the field.

    Basically there are two major differences between carbon composites and aluminum:
    1. Composites absorb high frequency vibrations (involving small deformations), but are are much stiffer to larger deformation;
    2. Cracks in composites do not propagate catastrophically, as is the case with aluminum.
    So mechanically, composites are likely superior for aviation applications as well.

    I would be much more interested in studying the comparative performance in the following areas.
    a). Emergency access to aircraft, if cutting of the skin is required. Composites are notiriously difficult to cut open.
    b). Chemical and mechanical stability in a burning aircraft. I don't think there's much or any field data of this sort.
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  3. jbcarioca
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    jbcarioca Gold Member

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    Although the B&&& has only about 9% composite, the cabin floor and rudder are composite as well as a number of other critical areas. In addition several nearly 100% composite aircraft have been produced including the Beech Starship which was 100% itself and the first such aircraft to be certified IIRC. From all the evidence to date it seems composites have no more and often less crash deficiencies than do traditional materials. I am no expert, to be sure, but I'm positive that the newer technologies from composites to complex metals (e.g. Glare) to FBW and fiber optics (B777 was the first finer optic network in a commercial airliner) are normally subjected to enormous scrutiny. And now, as we know, batteries are too... I do think the li-ion affair was a major departure from the norm of cautious new technology deployment.

    I know these statements can be attacked, in part justifiably...
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